we have
<u>The system of equations</u>
-------> equation 
-------> equation 
Substitute equation in equation
subtract 
both sides
Divide by 
both sides
the solution is the point 
therefore
the answer is
the solution to the system of equations is the point
If you have a calculator, you can use the inverse cos " cos⁻¹ " key. Many upper level books write that as Arccos so as not to confuse you with a negative exponent. We do that because if you take the cosine of any angle, and then the inverse cosine of any angle, it leads you back to the original angle. Think of it as a big "UNDO" button.
To one decimal place, that result is 61.6 degrees.
Basically, just find a common denominator. The LCD of 8 and 10 is 40 and that is divisible by 5, too. So the answer is 40 days.
